Specific Pathogen-free Guinea Pigs Research Articles

Impact of microbial diversity on inflammatory cytokines and respiratory pattern measured in whole-body plethysmography in guinea pig models.

This study investigates the breathing patterns and immune status of guinea pigs raised under specific pathogen-free (SPF) conditions compared to conventionally bred (CON). Breathing pattern parameters were assessed using whole-body plethysmography (WBP) during quiet breathing and saline nebulisation. Blood and bronchoalveolar lavage fluid (BALF) were analysed for white blood cell, neutrophil and eosinophil counts, and cytokine levels (TNF-α, IL-1β, IL-4). SPF guinea pigs exhibited higher tidal volume, expired volume, minute volume, and airflow parameters than CON guinea pigs. The immune analysis revealed lower white blood cell counts and IL-4 levels in SPF guinea pigs. These findings indicate that SPF guinea pigs have different respiratory and immune responses than CON guinea pigs. The study highlights that the maturation processes affecting breathing pattern parameters in SPF guinea pigs differ significantly from those in CON guinea pigs. This suggests potential limitations of SPF animals in respiratory physiology research due to their different immune and respiratory responses.

Role of green tea polyphenols in noise-induced hearing loss

Objective: To investigate the role and mechanism of action of green tea polyphenols in noise-induced hearing loss. Methods: Male specific pathogen-free guinea pigs were randomly divided into normal control group with 9 guinea pigs, noise exposure group with 36 guinea pigs, and green tea polyphenol intervention group with 36 guinea pigs. Auditory brainstem response (ABR) threshold shift was examined before noise exposure and at 1, 3, 7, and 14 days of noise exposure. The surface preparation of cochlear basilar membrane was used for hair cell count and the morphology of hair cells was also observed. Western blot was used to observe the expression of cysteinyl aspartate-specific protease-9 (caspase-9) and cysteinyl aspartate-specific protease-3 (caspase-3) in cochlear tissue. Results: Both the noise exposure group and the green tea polyphenol intervention group had an increase in ABR threshold after noise exposure, and the green tea polyphenol intervention group had a significantly lower ABR threshold shift than the noise exposure group at all time points (P<0.05). Both groups had enlargement, atrophy, or loss of hair cells after noise exposure, and at 7 and 14 days of noise exposure, the noise exposure group had a significantly higher rate of abnormal hair cells than the green tea polyphenol intervention group (P<0.05). Both groups had an increase in the expression of caspase-9 and caspase-3 after noise exposure, and the noise exposure group had a significantly greater increase than the green tea polyphenol intervention group (P<0.05). Conclusion: Green tea polyphenols can reduce noise-induced hearing loss and hair cell injury, possibly by regulating the expression of caspase-9 and caspase-3.

An improved abnormal toxicity test by using reference vaccine-specific body weight curves and histopathological data for monitoring vaccine quality and safety in Japan

Vaccines differ from other pharmaceutical products. The quality and safety of batches are regulated to high standards by national regulatory authorities. Various quality control and safety tests have been developed, including the abnormal toxicity test (ATT), which is described in the World Health Organization (WHO) guidelines and in each country's pharmacopoeia. However, the criteria for abnormal results are not well defined in these guidelines. In addition, the animal grade to be used in ATT, classified on the basis of microbial colonization, was not designated in either guideline. In this study, we report a new and improved method of performing ATT, including statistical, histopathological analysis and hematological findings. It is based on the observation that there are body weight changes characteristic to each vaccine, and such standardized changes can be used as references for evaluating test vaccines. In addition, histopathological data are useful for determining vaccine quality and safety. Combined with histopathological examination, the improved ATT will be of great use for evaluating the consistency, quality and safety of different batches of vaccine. The results of these analyses were similar using either ‘clean’ or specific pathogen-free guinea pigs.

Establishment of specific pathogen-free guinea-pig colonies using limited-flora guinea-pigs associated with conventional guinea-pig flora, and monitoring of their cecal flora.

Six groups of limited flora (LF) Hartley guinea-pigs were produced by inoculation of hysterectomy-derived GF guinea-pigs with various combinations of cecal bacteria of conventional (CV) guinea-pigs to determine the effective bacterial cocktails for the establishment of a specific pathogen free (SPF) colony. Bifidobacterium magnum (Bif) isolated from CV guinea-pigs was used for pretreatment. The mortality of LF guinea-pigs inoculated with only Bif was 75%, and that of those inoculated with Bif plus chloroform-treated cecal suspension (CHF) or Bif plus CHF plus 32 isolates from CV guinea-pigs was 40 to 66.7%. These three groups were in an unhealthy condition with mucoid enteritis-like diarrhea. However, the mortality of LF guinea-pigs inoculated with the anaerobic growth on EG plates injected with 10(-5) dilution of cecal contents (CF) or inoculated with Bif plus CF was 6.3 and 15%, respectively. These latter two groups of LF guinea-pigs were transferred to separate barrier rooms and some of the LF guinea-pigs were maintained in isolators as a source of intestinal flora for SPF guinea-pigs. The composition of cecal flora of LF guinea-pigs was stable for a long time, and bacteroidaceae and peptococcaceae were maintained as predominant components. The basic composition of the cecal flora of SPF guinea-pigs originated from LF guinea-pigs, which consists mainly of the anaerobic bacteria, was not changed over a long period, and the flora composition became similar to that in CV guinea-pigs. Guinea-pig-specific pathogens from the SPF colonies were not detected during experiments.

Evaluation of enzyme-linked immunosorbent assay for serodiagnosis of Bordetella bronchiseptica infection in guinea pigs

An enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of Bordetella bronchiseptica (B. bronchiseptica) infection in guinea pigs was evaluated. An isolate of B. bronchiseptica from lung lesion of a guinea pig was used as antigen after ultrasonication. In the experimental infection, specific pathogen-free guinea pigs inoculated with the bacterium intranasally were examined every 5 or 10 days. The organism was recovered from all animals between 5 and 30 days post-inoculation (p.i.). Only one animal was sero-positive by agglutination test 30 and 50 days p.i.; whereas, by ELISA, one animal was positive 5 days p.i., and all the animals showed strong reaction 20 to 50 (end of experiment) days p.i. Field samples obtained from 1983 to 1989 were tested by ELISA. The results corresponded to those of macroscopic observations and bacterial isolation. The ELISA proved to be useful method for detection of B. bronchiseptica infection in guinea pigs.

Effect of diet on non-specific antimicrobial resistance in Mycobacterium bovis BCG-vaccinated guinea pigs

Specific pathogen-free guinea pigs were maintained on purifieddiets low in protein (LP-10% ovalbumin; 50 ppm Zn); low in zinc (LZ-30% ovalbumin; <5 ppm Zn) or control (C-30% ovalbumin; 50 ppm Zn). Half of the animals in each diet group were vaccinated with viable Mycobacterium bovis BCG. Four and five weeks post-vaccination and diet initiation, guinea pigs from each of the 6 diet × vaccination groups were challenged with 10 3 viable Listeria monocytogenes per animal by the respiratory route and sacrificed four days later. Low protein guinea pigs demonstrated weight loss and reduced serum albumin levels. Low zinc animals were growth-retarded and had reduced plasma Zn levels. Neither LZ nor LP guinea pigs developed significant tuberculin reactions post-vaccination at either sacrifice interval. Non-specific acquired resistance against L. monocytogenes was enhanced in LP and LZ animals at 4 wks post- M. bovis BCG vaccination but not at the 5 wk interval. The anti-listeria resistance was most pronounced in the liver and spleen. While M. bovis BCG-vaccinated LP and LZ guinea pigs were incapable of expressing tuberculin hypersensitivity, they did develop a significant non-specific anti-listeria resistance.

Effect of protein and zinc deficiencies on vaccine efficacy in guinea pigs following pulmonary infection with Listeria.

Specific pathogen-free guinea pigs were maintained for 3 weeks on purified diets containing 30% protein (ovalbumin) and 50 ppm added zinc (Control-C), 10% protein and 50 ppm added zinc (low protein-LP), or 30% protein and no added zinc (low zinc-LZ). Half of the animals in each diet group were vaccinated intraperitoneally with 2.5 x 10(3) viable Listeria monocytogenes organisms after 8 days of diet treatment. Ten days later, all animals received an aerosol challenge of 250 L. monocytogenes organisms and were killed 4 days later. Both zinc and protein deficiency resulted in animals that were growth retarded as compared to controls. Specific nutrient effects were observed as significant reductions in total serum proteins (LP group) and plasma zinc concentrations (LZ group). In vaccinated guinea pigs, both protein and zinc deprivation resulted in significant impairment of delayed-type hypersensitivity (DTH) responses following the intradermal injection of listeria antigen. Diet did not exert a measurable impact on the response of nonvaccinated guinea pigs to pulmonary listeriosis. Prior vaccination allowed both malnourished groups to control the challenge infection successfully as measured by significant reductions in viable bacilli recovered from the lung, spleen and hilar lymph nodes. The diet and vaccine effect varied depending on the tissue examined. Thus, although both protein and zinc deficiencies resulted in loss of peripheral antigen-specific T lymphocyte function (DTH), vaccine efficacy was not impaired.

Respiratory infection with attenuated Mycobacterium tuberculosis H37Ra in malnourished guinea pigs.

Specific pathogen-free guinea pigs were infected via the respiratory route with viable, attenuated Mycobacterium tuberculosis H37Ra and maintained on purified isocaloric diets. The control diet contained 30% protein (ovalbumin) and 50 ppm of added zinc (50 micrograms/g), the low protein diet contained 10% protein and 50 ppm of added zinc, and the low zinc diet contained 30% protein and no added zinc. Guinea pigs from each diet treatment were skin tested with purified protein derivative 48 h before sacrifice at 3, 4, and 5 weeks postinfection. Protein-deficient animals exhibited significantly reduced body weight, spleen weight, serum total proteins, and serum albumin. Zinc deficiency was characterized by loss of weight and progressive reductions in plasma zinc concentrations. The number of viable M. tuberculosis H37Ra cells was significantly higher in the lungs of both malnourished groups at 3 weeks, but fell below control viable counts by 5 weeks postinfection. A similar pattern was seen in the spleens and bronchotracheal lymph nodes. Both the proportion and intensity of delayed hypersensitivity reactions increased steadily between 3 and 5 weeks in control animals, whereas the two malnourished groups were essentially anergic at all intervals, despite systemic infection. These results demonstrate that both protein and zinc deficiencies exert a significant influence on the development of pulmonary tuberculosis but that the nature of the influence depends upon the interval studied. In both malnourished groups, the pulmonary infection tended to peak early and decline, whereas the disease developed more slowly in control animals. Apparent control of mycobacterial populations in the tissues was accomplished by malnourished animals in the absence of demonstrable delayed hypersensitivity.

Immune Responses in Malnourished Guinea Pigs

Groups of specific pathogen-free guinea pigs were randomly assigned to purified, isocaloric diets containing either 30%, 20%, or 10% casein, or commercial stock diet. Each animal was vaccinated subcutaneously with viable bacille Calmette-Guerin (BCG). Seven weeks post-vaccination, groups of guinea pigs from each diet treatment were skin tested with purified protein derivative (PPD) and killed. Animals fed the 10% casein diet exhibited significant reductions in body weight, serum albumin, and hemoglobin levels. Significantly greater numbers of viable BCG were recovered from the inguinal lymph nodes of malnourished (10% casein) animals than from 30% casein or stock control groups. Skin test responses to PPD were completely absent or markedly suppressed in the 20% and 10% casein groups. Lymphocyte blastogenesis following in vitro stimulation of peripheral blood lymphocytes with a polyclonal T cell mitogen was also reduced in the 10% casein group. Circulating levels of serum IgM and C3 complement were not influenced by nutritional status while levels of IgG were elevated in 10% and 20% casein groups. These results suggest that malnutrition may impair cell-mediated immune responses on which the efficacy of BCG vaccine depends.malnutrition cell-mediated immunity BCG vaccine

The influence of fluocortolone treatment on the collagen content in guinea pig skin.

Specific pathogen free guinea pigs were treated with varying dosis of fluocortolone for 15 days. The treated animals showed the same per cent weight gain as the controls. The total hydroxyproline content of the skin and the hydroxyproline content in different collagen fractions was the same in treated and untreated animals. Thus fluocortolone seems to have no specific effect on the synthesis or the breakdown of collagen in the guinea pig skin. Also the physical development of the animals, kept under defined conditions, failed to show a catabolic effect of of fluorcortolone.